Valid email addresses have a well-known structure (i.e. [A-z.]*_NAME) so,
for example [EMAIL PROTECTED] is clearly a bogus address.
Off the top of my head you might be able to do something like (untested):
header __GOOD_NAME To =~
/[A-Za-z]{1,30}_[A-Za-z\d\.]{2,40}\@(?i:domain\.com)/
meta BAD_NAME !__GOOD_NAME
score BAD_NAME 2
Above is based on the assumption that "NAME" includes only letters, numbers,
and dots. If it can also have underscores then you could just do \w{2,40}
or the like for the second part.
Loren